Electric motor driven liquid pump, in particular for the forced lubrication of a manual transmission for motor vehicles

ABSTRACT

An electric motor driven fluid pump for forced lubrication of a manual transmission of a motor vehicle, includes a housing having a fluid inlet and a fluid outlet, and an electronically commutated electric motor incorporated therein. The electric motor has a substantially cup-shaped magnetic rotor rotatable around a rotational axis, shaped for conveying fluid, an annular stator having a motor winding which at least partially encloses the rotor in a coaxial arrangement with respect to the rotational axis when viewed along the rotational axis, and a magnetic field sensor for detecting the position of the rotor. The housing includes a stator housing section which holds the stator, separates same from a liquid chamber in which the rotor is arranged, and extends into the rotor by a housing offset formed for receiving the magnetic field sensor.

TECHNICAL FIELD

The present invention relates to an electric motor driven liquid pump. In particular, the invention relates to a liquid pump such as used on a large scale in modern motor vehicles for the forced lubrication of manual transmissions.

A manual transmission, which is arranged in the motor vehicle in a drive train between an internal combustion engine and vehicle wheels to be driven, has a lubricant system for lubrication by a lubricant such as transmission oil, which lubricant system serves the purpose of fetching the lubricant from a lubricant sump in the transmission housing to areas to be lubricated. Included in the latter are, in particular, meshing gearwheels and bearings for rotating parts, particularly shafts and gearwheels.

In conventional lubricant systems in manual transmissions distinction is basically made between splash lubrication, in which the gearwheels ‘splash’ in the lubricant sump and during further rotation distribute the lubricant to the gearwheels and bearings, and forced lubrication by one or more pumps, which convey the lubricant from the lubricant sump by way of a duct system to the places to be lubricated. If forced lubrication alone is provided, i.e. none of the gearwheels intentionally dips into the lubricant sump, this is termed ‘dry sump lubrication’, which by comparison with splash lubrication or combined lubrication has the advantage that there is no induction of air into the lubricant by the gearwheels and thus no formation of oil foam, which can lead to disruptions in the transmission lubrication. In addition, in manual transmissions with dry sump lubrication so-called ‘splash losses’ impairing transmission efficiency are avoided.

PRIOR ART

Electric motor driven lubricant pumps are already used in the prior art for the lubricant system of manual transmissions with dry sump lubrication (see, for example, document DE-A-10 2005 005 154). Distinction has to be made here between lubricant systems in which the lubricant is conveyed by the pump—usually a gear pump—under pressure to nozzles, by way of which the lubricant is sprayed on the places to be lubricated, and lubricant systems with a pump—for example a centrifugal pump—by which the lubricant is merely conveyed to a distributor with a reservoir, from where the lubricant substantially free of pressure rains down or drips onto mesh zones and bearing locations. The last-mentioned, low-pressure lubricant system represents the field of pump use preferred here, in particular because it offers cost advantages by comparison with the solution involving pressure. Thus, a filter arrangement for avoidance of nozzle blockage is redundant, susceptibility to contamination is less overall, lower motor power can be provided for the electric motor, etc.

Constructional details of an electric motor driven centrifugal pump for lubricant supply of a transmission are evident from, for example, document DE-A-10 2007 018 504 (FIG. 7). In this instance an electric motor and a pump driven by it form a motor/pump unit, which is arranged directly in the lubricant (‘operating medium’ in the terminology of this document) below a liquid level. The electric motor and the pump in this prior art lie in succession and the motor/pump unit is additionally surrounded by a duct system serving the purpose of conducting the intake flow along the surface of the electric motor, which heats up due to operation, to a suction port of the pump. Heat transfer is to be improved and the lubricant heated by thermal contact between the electric motor and the lubricant conducted therealong, so that the viscosity of the lubricant is reduced and thus also the intake resistance. As a result, the conveying rate of the pump is to be increased and thus the quantity of lubricant supplied to the lubricating points; in addition, a downward extension of the temperature range at which the pump can still reliably convey lubricant is intended. A disadvantage of this prior art, however, is that the motor/pump unit together with the duct system therearound demands a relatively large amount of space not only in radial direction, but also in axial direction. However, the available installation space at the bottom of the transmission housing is usually very tightly dimensioned.

In addition, an electric motor driven oil booster pump arranged within an oil pan of an automatic transmission is known from document DE-A-10 2006 012 838 (FIG. 3c). In this prior art, as well, the pump and the electric motor lie in succession, the latter being located outside the oil pan. In that case, drive of the pump takes place mechanically by way of a shaft which passes through the wall of the oil pan and is sealed relative to this wall. This arrangement of pump and electric motor in succession also demands a relatively large amount of space. Moreover, use is preferably made of a brush motor, which, as such, necessarily has to be arranged outside the oil chamber and in addition is susceptible to wear.

Moreover, documents DE-A-199 34 382 and DE-A-199 56 380 disclose liquid pumps usable as cooling water pumps for the cooling circuit/heating circuit of a motor vehicle. These liquid pumps have an integrated electric motor with a stator and a rotor, the stator being a claw pole stator and the rotor forming an impeller of the pump. In this prior art (DE-A-199 34 382: column 3, lines 47 to 51; DE-A-199 45 380: column 4, lines 17 to 22) a magnetic field sensor (not illustrated) can be provided, particularly for commutation of the electric motor, at a location (not specified in more detail) where it is exposed to the variable magnetic field of the rotating rotor.

Similarly, an electric motor driven water pump is known from DE-A-10 2009 049 904 (FIG. 1), in which a partition sealingly arranged between a stator and a rotor unit is constructed in a simpler and more economic manner from a corrosion-resistant material capable of being deep drawn. In that case, a substantially hollow conical retaining element is integrally formed at a central location of the partition, which element is provided on its side facing the rotor unit with a spherical bearing surface for a spherical slide body for mounting the rotor unit and on its side remote from the rotor unit bounds a cavity in which a temperature and/or magnetic field sensor (not illustrated) can be received (see claims 9 and 10 as well as the Abstract [0027] of the description), so that the bearing points for the rotor unit and the sensor are necessarily arranged axially in succession with respect to the axis of rotation of the pump.

Finally, further electric motor driven pumps which are, however, of relatively lengthy construction as seen along the pump rotational axis and which are used as, in particular, water pumps in heating circuits are evident from documents DE-A-100 45 597 (FIGS. 7 and 8) and DE-A-100 52 797 (FIG. 1).

OBJECT

The invention has the object of providing, particularly for forced lubrication of a manual transmission for motor vehicles, an electric motor driven liquid pump which avoids the above disadvantages and in particular has by comparison with the outlined prior art, in a more economic design, a lower constructional height.

ILLUSTRATION OF THE INVENTION

This object is fulfilled by the features indicated in claim 1. Advantageous or expedient developments of the invention are the subject matter of claims 2 to 15.

An electric motor driven liquid pump according to the invention, which is usable particularly for forced lubrication of a manual transmission for motor vehicles, comprises a housing, which has a liquid inlet and a liquid outlet, and an electronically commutated electric motor, which is received therein and which comprises a substantially cup-shaped magnetic rotor, which is rotatable about an axis of rotation, with means for conveying liquid, an annular stator, which has a motor winding and which as seen along the axis of rotation at least partly surrounds the rotor in coaxial arrangement with respect to the axis of rotation, and a magnetic field sensor for positional recognition of the rotor, wherein the housing has a stator housing section which carries the stator, separates this from a liquid chamber in which the rotor is arranged and as seen along the axis of rotation extends into the rotor by a housing offset constructed for reception of the magnetic field sensor.

Due to the fact that from the start the drive of the liquid pump according to the invention is formed by an electronically commutated electric motor as distinct from a brush motor, the susceptibility to wear and disturbance as discussed above with respect to the prior art is absent; the liquid pump can also be freely positioned, for example in or directly at an oil chamber of a manual transmission.

In that regard, a particularly compact constructional form is favored at the outset if the rotor is both a pump component (means for liquid conveying) and a motor component (magnetic). Any form of (co-)rotating connection between the drive side and the pump side is thus redundant. Moreover, with respect to low constructional height of a liquid pump according to the invention, the design of the stator housing section, which also separates media in the pump housing, has a special role: on the one hand, the stator housing section carries the annular stator in such a way that this covers the cup-shaped rotor at least partly as seen in axial direction. On the other hand, the stator housing section has the housing offset which protrudes into the cup-shaped rotor and at which the magnetic field sensor for the electronic commutation is received. Through this quasi ‘nested’ arrangement of the components relevant to drive substantially in the rotor plane with utilization as well of the rotor internal area, the liquid pump has a very flat construction. In other words, by contrast to the prior art outlined further above a pure arrangement of the individual components in succession is not present, but rather an arrangement thereof ‘one in the other’.

In an advantageous development of the liquid pump the housing can be flange-mounted on a liquid container by way of a flange surface external to the pump and can have in multi-part construction, apart from the stator housing section, a pump housing section, which has the liquid inlet and liquid outlet and which together with the stator housing section bounds the liquid chamber, and a motor housing section, which together with the stator housing section bounds an electronics chamber in which at least the stator is disposed. In this embodiment the pump housing comprises, in a simpler and more assembly-friendly manner, only a minimum of housing components to separate ‘wet’ regions of the pump from ‘dry’ regions of the pump and to bound the latter overall relative to the liquid or environment/atmosphere, namely (a) the pump housing section as a boundary, which is permeable in defined manner by way of the liquid inlet and outlet, for the liquid, (b) the stator housing section as a media-separating boundary between the ‘wet’ liquid chamber and the ‘dry’ electronics chamber in the pump and (c) the motor housing section as a boundary relative to the rest of the environment/atmosphere.

In principle, the housing components of the liquid pump can consist of a light metal such as, for example, an aluminum alloy. However, with regard to low production costs it is preferred if the housing components are executed as plastics material parts, which can be produced by injection technology, i.e. by plastics material injection molding. A screw connection, rivet connection or snap connection, for example, is conceivable for fastening the housing components to one another. However, for a particularly economic housing design it is preferred if the pump-housing and motor-housing sections produced as plastics material parts are welded together.

Moreover, the stator housing section can have, with respect to a simple and axially as well as radially positionally precise fastening in the housing of the liquid pump, a stator housing flange which is clamped in place between the pump housing section and the motor housing section and which (additionally) centers the stator housing section at the motor housing section with respect to the axis of rotation of the rotor.

In a particularly preferred embodiment of the liquid pump a sealing element can be provided, which—in multi-functional manner—at the same time (firstly) seals relative to the liquid container at the flange surface of the housing external to the pump (‘pump external’ separation between liquid and environment/atmosphere), (secondly) separates the liquid chamber from the electronics chamber (‘pump internal’ media separation) and (thirdly) seals the electronics chamber relative to the environment (sealing against penetration of moisture or contamination of the pump).

By contrast to the current prior art, a multiplicity of seal inserts is not required and does not have to be handled and the disadvantages connected therewith (assembly cost, risk of ‘migration’ of individual seals, etc.) are avoided without alternative measures such as, for example, sealed welding of housing components having to be provided at the housing. Since, in addition, the pump already carries the means for sealing ‘external to pump’, the assembly/flange-mounting of the pump at the liquid container is simple in form. As a result, an inexpensive pump sealing which has process security and thus also reliability can be achieved.

In that regard, the flange surface, which is external to the pump, of the housing can be provided with an encircling groove for receiving a first sealing section of the sealing element, which protrudes by at least one sealing lip, but preferably two sealing lips, beyond the flange surface external to the pump so as to seal relative to the liquid container. A double sealing of that kind seals in a manner which is particularly insensitive to contamination and reliable. Scratches or the like at the flange surface of the liquid container can be ‘bridged over’; consequently, there are no special demands on cleanliness or smoothness of the flange surface.

Moreover, the arrangement can be such that the pump housing section has a pump housing flange at which the flange surface external to the pump and a flange surface internal to the pump are formed at opposite sides, which flange surface internal to the pump is provided with an encircling groove for receiving a second sealing section of the sealing element and which second sealing section protrudes by two sealing lips beyond the flange surface internal to the pump, wherein—in a clearer and unique functional assignment of the sealing lips—one sealing lip co-operates with the stator housing section in order to separate the liquid chamber from the electronics chamber, whilst the other sealing lip co-operates with the motor housing section in order to seal the electronics chamber relative to the environment. In that case, the sealing lips can advantageously compensate for different housing thicknesses—which may differ only due to tolerances—in the flange regions of the stator housing section and the motor housing section.

In addition, the sealing element, consisting of an elastomeric material, can be attached to the pump housing section so that the sealing element is, in a more assembly-friendly manner, a captive component of the liquid pump. In principle, the sealing element can in that case be incorporated in or plugged onto the pump housing section. However, with respect to simple capability of production and process reliability (avoidance of assembly errors) it is preferred if the sealing element is injection-molded at the pump housing section to be interlocking.

For a reliable mechanically positive fixing of the sealing element to the pump housing section there can be provided between the encircling groove at the flange surface external to the pump and the encircling groove at the flange surface internal to the pump a plurality of openings which are spaced apart in circumferential direction and through which the elastomeric material of the sealing element is injection-molded in order to connect the first sealing section and the second sealing section of the sealing element together. The sealing element can thus advantageously be injection-molded on the pump housing section in one working step. In the case of an overlapping or a congruent arrangement of the grooves on the two sides of the pump housing flange the sealing arrangement is also a very compact construction in radial direction. Beyond that, such an arrangement, in which sealing with respect to two sides takes place quasi on one diameter, has the advantage that even in the case of relative ‘soft’ or flexible housing components the risk of leakages due to housing deformation is minimized.

In an advantageous development of the liquid pump, pole sheets of the stator can be embedded in the stator housing section, which consists of a plastics material, by plastics material injection-molding encapsulation. As a result, an optimum heat dissipation from the motor winding and pole sheets to the liquid chamber is made possible. At the same time, the motor winding is electrically insulated by the injection-molded encapsulating plastics material.

In further pursuance of the concept of the invention a temperature sensor can be integrated, preferably near the liquid outlet, in the housing of the liquid pump, in particular received in a receiving recess in the stator housing section, as a result of which an external temperature sensor and the (assembly) cost connected therewith are eliminated in all cases. Through detection of the temperature of the conveyed liquid, a conclusion can be made about its viscosity—which in the case of oil is important for the lubricating effect thereof—together with the need for cooling and the rotational speed of the electric motor can be suitably controlled, in which regard, for example, a tendency to higher temperatures signals a greater need for cooling and thus a requirement for higher pump rotational speeds. Positioning of the temperature sensor near the liquid outlet additionally has the advantage that the temperature detected thereat makes a statement of greatest validity with respect to the characteristics of the liquid delivered by the pump; moreover, there is no risk of erroneous detection due to heat build-up at the liquid outlet as a consequence of the liquid flow taking place thereat when conveying takes place.

Further, an electronic circuit board can be integrated in the housing, which circuit board carries at least the electronic components necessary for electronic commutation of the electric motor as well as optionally the sensor elements and with which contact by the electrical parts of the liquid pump is made by way of press-fit connections. By comparison with welded or soldered connections, which are equally conceivable, press-fit connections can be produced at lower cost.

In a preferred and similarly particularly compact embodiment of the liquid pump the liquid outlet of the housing can in addition be oriented transversely to the axis of rotation of the rotor. Such a radial feed for the liquid to be conveyed functions without problem and without inducting air even in the case of a very low liquid level.

Moreover, it can be provided that the rotor has a permanently magnetic outer cylinder selection, which co-operates with the motor winding, as well as, on the side remote from the housing offset of the stator housing section, a base section which is formed as an impeller and which is injection-molded from a magnetic material, which is incorporated in plastic, directly onto a rotor shaft rotatably mounted in the housing. On the one hand, such a rotor can be produced particularly economically. On the other hand, such a shaft solution has advantages—by comparison with an axle solution which is equally conceivable in principle and in which the rotor rotates on an axis fixed relative to a housing—of such a kind that a bearing shank or the like at the rotor for provision of a sufficient supporting length is redundant, which in turn is conducive to a short constructional length, and the rotational mounting of the rotor shaft in the housing leads to bearing points which are further apart, this being beneficial for good rotation of the rotor.

In principle, the bearing points can in that case ultimately be formed by bearing bushes or the like let into the housing. However, with respect to low costs it is preferred if the rotor shaft is mounted on either side of the base section at least radially directly in the housing, in particular on the one hand in the housing offset of the stator housing section and on the other hand in a bearing extension of the pump housing section.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail in the following by way of preferred embodiments with reference to the accompanying—in part schematic—drawings, in which for simplification of the illustration elastomeric or elastic parts are illustrated in undeformed state and in which:

FIG. 1 shows a perspective view of an electric motor driven liquid pump according to a preferred first embodiment of the invention, in non-mounted state, obliquely from above and the left front with a view onto a flange surface, which is external to the pump, for fastening to a liquid container such as, for example, a transmission housing;

FIG. 2 shows a plan view of the liquid pump according to FIG. 1, from above in FIG. 1;

FIG. 3 shows a sectional view, which is to enlarged scale by comparison with the scale of FIG. 2, of the liquid pump according to FIG. 1 in correspondence with the doubly-stepped section line III-III in FIG. 2 in a state of mounting on a transmission housing, which is illustrated in broken-away form;

FIG. 4 shows a part sectional view, to a further enlarged scale, of the liquid pump according to FIG. 1 in correspondence with the detail circle IV in FIG. 3, for better illustration of an encircling sealing element with a triple function;

FIG. 5 shows a sectional view, which is to enlarged scale by comparison with the scale of FIG. 2, of the liquid pump according to FIG. 1 in correspondence with the section line V-V in FIG. 2;

FIG. 6 shows a sectional view, which is to enlarged scale by comparison with the scale of FIG. 3, of the liquid pump according to FIG. 1 in correspondence with the doubly-stepped section line VI-VI in FIG. 3, but by contrast to FIG. 3 in non-mounted state, i.e. without transmission housing and fastening means; and

FIG. 7 shows a longitudinal sectional view of an electric motor driven liquid pump according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the figures the reference numeral 10 designates in general an electric motor driven liquid pump for forced lubrication of a manual transmission for motor vehicles, of which in FIG. 3 merely a lower part, namely a transmission housing 12 (also) serving as a liquid container, is illustrated in broken-away form. The liquid pump 10 is mounted from the outside on the transmission housing 12, more precisely flange-mounted by way of a flange surface 14, which is external to the pump, of a housing 16 of the liquid pump 10, so that a liquid inlet 18 and a liquid outlet 20 of the liquid pump 10 protrude into the transmission housing 12 through an opening 22 in the transmission housing 12. Whereas the liquid inlet 18 is disposed below a transmission oil fill level, which is indicated in FIG. 3 by a horizontal line at 24, in the transmission housing 12, the liquid outlet 20 extends out at the top above the transmission oil fill level 24, where it is in fluid connection—in a way which is not shown here—with the distributor system (not illustrated) for the transmission oil.

An electronically commutated electric motor 26 is received in the housing 16 (see FIGS. 3 and 5) and comprises a substantially cup-shaped, magnetic motor 28, which is rotatable about an axis A of rotation and is provided at the end with a plurality of curved blade projections 30 (cf., in particular, FIG. 6) as means for conveying liquid, a stator 34 having a motor winding 32, and a magnetic field sensor 36—which is required in a manner known per se for the electronic commutation—for recognition of the rotational angle position of the rotor 28 (see FIG. 3). In that regard, the housing 16 is of multi-part, more precisely three-part, construction with an upper pump housing section 38, which has the liquid inlet 18 and the liquid outlet 20, a middle stator housing section 40, which carries the annular stator 34 so that this at least partly surrounds the rotor 28 in coaxial arrangement with respect to the axis A of rotation as seen along the axis A of rotation and bounds together with the pump housing section 38 a liquid chamber 42 in which the rotor 28 is arranged by its blade projections 30, and a lower motor housing section 44, which together with the stator housing section 40 bounds an electronics chamber 46 in which, inter alia, the stator 34 is located.

In a particularly compact embodiment the stator housing section 40 extends, as seen along the axis A of rotation, into the rotor 28 by a housing offset 48, which is constructed for reception of the magnetic field sensor 36. In addition, as will be similarly described in more detail in the following, a sealing element 50 is provided at the housing 16, which sealing element in a triple function simultaneously seals at the flange surface 14, which is external to the pump, of the housing 16 relative to the transmission housing 12, separates the liquid chamber 42 from the electronics chamber 46 and seals the electronics chamber 46 with respect to the environment.

Further details with respect to the pump housing section 38, which is constructed as a plastics material part from a laser-transparent, glass-fiber-reinforced polyphthalamide (PPA 35 GF), can be inferred from, in particular FIGS. 3, 5 and 6. Accordingly, the pump housing section 38 has, radially outwardly, a pump housing flange 52 at which the flange surface 14 external to the pump and the flange surface 54 internal to the pump are formed on opposite sides. The sealing element 50 consisting of an elastomeric material is secured to the pump housing flange 52 of the pump housing section 38 in a manner still to be described.

The pump housing section 38 is formed with a dome-like elevation radially within the pump housing flange 52 and bounds, in part together with the rotor 28 and the stator housing section 40, in the region of the liquid chamber 42 a pump channel 56 which can be substantially divided into four regions, namely—as seen in direction from radially inwardly to radially outwardly—(1st) a central, i.e. centered with respect to the axis A of rotation, substantially funnel-shaped inlet region 58 (see, in particular, FIG. 5), (2nd) a central substantially annular acceleration region 60 in which the blade projections 30 of the rotor 28 move in operation of the liquid pump 10, and (3rd) a substantially screw-shaped conveying region 62 (see, for this purpose, also FIGS. 1 and 2), which finally (4th) opens into a tubular outlet region 64 which extends adjacent to the pump housing flange 52 substantially parallel to the axis A of rotation. The substantially funnel-shaped inlet region 58, which axially protrudes relative to the central acceleration region 60 of the pump channel 56, forms the liquid inlet 18 of the housing 16 at the outer circumferential side, which inlet is thus oriented substantially transversely to the axis A of rotation at the rotor 28 and by way of which—as can be best seen in FIGS. 1 and 2—the liquid (here the transmission oil) can run into the liquid pump 10 over almost the full circumference (approximately 360°), i.e. interrupted only by three webs 66 extending in radial direction. In the funnel-shaped inlet region 58 the liquid then undergoes a flow deflection through 90° (from radially in the direction of the axis A of rotation to axially along the axis A of rotation) until it impinges on the rotor 28 with its blade projections 30, where a further flow deflection through approximately 90° takes place (from axially along the axis A of rotation to radially away from the axis A of rotation). In the central acceleration region 60 of the pump channel 56, which as seen in section (FIGS. 3, 5) is bounded on opposite sides in axial direction by the pump housing section 38 and the rotor 28 to have an approximately constant flow cross-section, the liquid is then as a consequence of the shape of the blade projections 30 accelerated radially outwardly and in circumferential direction in correspondence with the rotational direction R of the rotor 28 (see FIG. 6), after which it passes into the substantially screw-shaped conveying region 62. In the conveying region 62 of the pump channel 56, which is bounded on one axial side by (at the start) the rotor 28 and the stator housing section 40 and on the other axial side as well as at the circumference by the pump housing section 38 to have a flow cross-section increasing in correspondence with the course of the screw as seen in rotational direction R, the liquid is then conveyed substantially in circumferential direction to the tubular outlet region 64. At the start of the outlet region 64 a flow deflection of the liquid through approximately 90° (from substantially in circumferential direction to axially parallel to the axis A of rotation) then takes place once again, after which the liquid flows along the constant circular flow cross-section of the outlet region 64 in order to finally be delivered by the liquid pump 10 by way of the liquid outlet 20 formed by the outlet region 64.

According to FIGS. 3 and 5 the pump housing section 38 additionally has at a central zone, i.e. adjoining the inlet region 58, a bearing projection 68 for mounting—which is still to be described—the rotor 28. So far as the connection of the injection-molded pump housing section 38 with the other parts of the housing 16 is concerned, it must finally be mentioned with respect to the pump housing section 38 that the pump housing flange 52 is provided radially outwardly of the flange surface 54 internal to the pump and adjoining this with an encircling groove 70 for receiving an encircling collar 72, which is formed to be substantially complementary as seen in plan view, at the motor housing section 44. Moreover, the pump housing section 38 has, according to FIGS. 1, 2 and 6, mounts (in FIG. 6 with a dowel centrally at the bottom and a slot at the top right) at 74 for positioning pins 76 (again see FIG. 6) formed at the stator housing section 40, which pins serve the purpose of aligning the stator housing section 40 with respect to the pump housing section 38.

The motor housing section 44, which is similarly injection-molded as a plastics material part from a glass-fiber reinforced polyphthalamide (PPA 50 GF), is laser-welded to the pump housing section 38—suitably aligned indirectly by way of the stator housing section 40—and in particular with its collar 72 encircling in the groove 70 of the pump housing flange 52 (indicated in FIG. 4 by the cross-hatching at the base of the groove 70). In that case, according to FIGS. 4 and 5 the pump housing section 38 is supported by way of the flange surface 54, which is internal to the pump, of the pump housing flange 52 on an encircling shoulder 78, which adjoins the collar 72 radially inwardly, of the motor housing section 44.

In the illustrated embodiment the motor housing section 44 has, radially outwardly, four fastening eyes 80 which are each lined by a metallic sleeve 82 encapsulated in interlocking manner by injection-molding. As illustrated in FIG. 3, the sleeves 82 in the mounted state of the liquid pump 10 are penetrated by cap screws 84, which are screwed into respectively associated threaded bores 86—which are distributed around the opening 22—in the transmission housing 12 in order to attach the liquid pump 10 from the outside to the transmission housing 12 and in that case to also firmly connect the individual parts of the housing 16 together. On the other hand, the weld connection between pump housing section 38 and motor housing section 44 as discussed above serves primarily as securing during transport.

The motor housing section 44 is provided between the fastening eyes 80 on the left in FIGS. 1, 2 and 6 with a plug collar 88 for an electric terminal of the liquid pump 10. In this respect, there can be seen in the section according to FIG. 5 by way of example that electrical conductors 90 are let into or injection-molded in the motor housing section 44, which conductors extend from the region of the plug collar 88 into the electronics chamber 46. The sectional views according to FIGS. 4 and 5 also show that an electronic circuit board 92 with electronic components, which are known per se and necessary for the pump control, is integrated in the electronics chamber 46 of the housing 16. The electronic circuit board 92 itself is contacted relative to the electrical conductors 90 in the motor housing section 44 by way of press-fit connections, of which in FIG. 5 one connection is shown at 94, and is supported on projections 96, which are internally formed at the motor housing section 44 and to which the electronic circuit board 92 is additionally attached, in part by screws 98. Analogously to the positioning pins 76 for the pump housing section 38, the stator housing section 40 also has positioning pins (not able to be seen here), which are at the bottom in FIGS. 3 and 5 and which engage in associated holes (dowel hole and slot; not shown in the figures) in the motor housing section 44 and in that case extend through corresponding holes (not illustrated) in the electronic circuit board 92. The electrical parts of the liquid pump 10 are similarly contacted by way of press-fit connections 94 relative to the electronic circuit board 92; of those, there is shown in FIG. 3 by way of example merely the press-fit connection 94 for a further electrical conductor 90, which is let into or injection-molded in the stator housing section 40 and with which a temperature sensor 100 is connected. Corresponding electrical connections (not illustrated in more detail) are present for the motor winding 32 and for the magnetic field sensor 36.

The stator housing section 40 is also injection-molded as a plastics material part from a glass-fiber-reinforced polyphthalamide (PPA 50 GF). In that regard, not only the said electrical conductors 90, but also the pole sheets 102 of the stator 34 are embedded by injection-molding encapsulation by the plastics material of the stator housing section 40. Only after the injection-molding process is the motor winding 32 mounted, which is economically constructed as an orthogonal layer winding. The stator 34 is completed by a slotted (not shown) metallic ground ring 104, which is drawn with friction fit onto radially outwardly protruding edges of the pole sheets 102 and in addition connected by crimping with the edges of the pole sheets 102 (not visible in the figures).

The region, which carries the stator 34, of the stator housing section 40 surrounds the central housing offset 48 of the stator housing section 40 in coaxial positional relationship with respect to the axis A of rotation while leaving an annular space 106 into which the rotor 28 enters. According to FIG. 3, the housing offset 48 is provided at a radially outwardly disposed position thereof, i.e. at a radial spacing from the axis A of rotation, with a recess 108, which is open towards the motor housing section 44, for reception of the magnetic field sensor 36, which can be, for example, a Hall element. According to FIGS. 3 and 5, a further bearing projection 110 for journaling the rotor 28 is provided at the housing offset 48, which is substantially cup-shaped in the illustrated embodiment, of the stator housing section 40 on the side remote from the pump housing section 38. The recess 108 for receiving the magnetic field sensor 36 and the bearing position formed by the bearing projection 110 thus lie within the rotor 28 at a spacing, but adjacent to one another, in a plane extending transversely to the axis A of rotation. This ‘radial arrangement adjacent to one another’ of the said functional elements is also beneficial for the flat constructional form of the liquid pump 10. Beyond that, the magnetic field sensor 36 is arranged near the outer wall of the rotor 28, which by virtue of the spacing of maximum size from the axis A of rotation on the one hand and the proximity to the rotor 28 on the other hand is conducive to a good quality of the detected signal.

According to FIGS. 2, 3 and 6, in addition a sub-region 112 of the stator housing section 40 protrudes, as seen in radial direction, adjacent to the stator 34 and axially in direction of the pump housing section 38 in ramp-like manner beyond the rest of the stator housing section 40 and thus forms a ‘soft’ transition, which reduces power losses, between the screw-shaped conveying region 62 and the tubular outlet region 64 of the pump channel 56. According to FIGS. 3 and 6 this sub-region 112 of the stator housing section 40 is provided with a receiving recess 114, which is open towards the motor housing section 44, for the temperature sensor 100 so that the latter is integrated in the housing 16 of the liquid pump 10 near the liquid outlet 20.

Finally, the stator housing section 40 has, radially outwardly, a stator housing flange 116 which is clamped in place in sandwich-like manner between the pump housing section 38 and the motor housing section 44 and which radially centers the stator housing section 40 in an associated step 118 at the motor housing section 44 with respect to the axis A of rotation.

Further details with respect to the encircling sealing element 50, which for simplification of the illustration is shown undeformed, are evident from, in particular, FIGS. 4 and 6. According to those, the pump housing flange 52 of the pump housing section 38 starting from the flange surface 14, which is external to the pump, of the housing 16 is provided with an encircling depression or groove 120 for reception of a first sealing section 122 of the sealing element 50, which protrudes by two sealing lips 124, 126, i.e. a radially inner sealing lip 124 and a radially outer sealing lip 126, beyond the flange surface 14 external to the pump so as to provide sealing relative to the transmission housing 12. Moreover, the pump housing flange 52 starting from the flange surface 54 internal to the pump is provided with a further encircling depression or groove 128 for receiving a second sealing section 130 of the sealing element 50. The latter protrudes by two sealing lips 132, 134 beyond the flange surface 54 internal to the pump, of which one, radially inner sealing lip 132 co-operates with the stator housing flange 116 of the stator housing section 40 so as to separate the liquid chamber 42 from the electronics chamber 46. The other, radially outer sealing lip 134, thereagainst, co-operates with an associated shoulder 136 of the motor housing section 44 so as to seal off the electronics chamber 46 from the environment. In that case, the second sealing section 130 of the sealing element 50 extends over or covers the central region between the stator housing flange 116 of the stator housing section 40 and the step 118 at the motor housing section 44 in radial direction with respect to the axis A of rotation of the rotor 28, in which case as a consequence of deformation of the sealing lips 132, 134 a defined biasing force is also produced between the individual parts of the housing 16.

In the illustrated embodiment the sealing element 50 is injection-molded at the pump housing flange 52 of the pump housing section 38 to be interlocking. For that purpose, formed in the pump housing flange 52 between the encircling groove 120 at the flange surface 14 external to the pump and the encircling groove 128 at the flange surface 54 internal to the pump is a plurality of openings 138, which are preferably uniformly spaced apart in the circumferential direction, i.e. as seen along the grooves 120, 128, and which connect the grooves and are penetrated by the elastomeric material of the sealing element 50 by injection molding so as to interconnect the first sealing section 122 and the second sealing section 130 of the sealing element 50 by way of a material bond.

Finally, further details with respect to the rotor 28 and the mounting thereof in the housing 16 are shown by, in particular, FIG. 5. The rotor 28 has a permanently magnetic outer cylinder section 140, which co-operates in a manner known per se with the motor winding 32 of the stator 34, as well as a base section 142 constructed as an impeller with the blade projections 30 on the side remote from the housing offset 48 of the stator housing section 40, and consists of a magnetic material which is incorporated in plastics material and which is directly injection-molded on a metallic (preferably steel) rotor shaft 144, which is rotatably mounted in the housing 16, with conjunctive formation of the blade projections 30. The rotor shaft 144 is journaled radially directly, i.e. without bearing bushes or the like, in the housing 16 on either side of the base section 142, namely on the one hand in a cylindrical recess 146 at the bearing projection 110 in the housing offset 48 of the stator housing section 40 and on the other hand in a cylindrical recess 148 at the bearing projection 68 of the pump housing section 38. In that regard, the rotor shaft 144 is supported in FIG. 5 axially at the bottom, i.e. at the end, on the base of the recess 146 in the bearing projection 110. In FIG. 5 at the top a thrust washer surrounding the rotor shaft 144 can be provided between the base section 142 of the rotor 28 and the bearing projection 68, by way of which washer the rotor 28 is axially supported, in operation of the liquid pump 10, at the bearing projection 68 when the rotor 28 is raised against gravitational force due to the pressure conditions arising thereat.

In the following, the liquid pump 10 according to the second embodiment shall be described with reference to FIG. 7 only to the extent that it differs significantly from the first embodiment described in detail above with reference to FIGS. 1 to 6. In that regard, the same reference numerals designate components or subassemblies of the second embodiment the same as or corresponding with those of the first embodiment.

The significant differences here consist of the construction of the stator housing section 40 in the region of the rotor 28 and the mounting—which is at the bottom in FIG. 7—of the rotor 28 at the stator housing section 40. In the second embodiment the housing offset 48 is not formed to be substantially cup-shaped, but has two sections, which are formed integrally at the stator housing section 40 by way of a base 151, the base being circular in plan view as seen in the direction of the axis A of rotation, and by which the housing offset 48—again as seen along the axis A of rotation—extends into the rotor 28, namely a central bearing section 152 and a sensor section 154, which is radially spaced from the bearing section 152 with respect to the axis A of rotation, in the vicinity of the cylinder section 140 of the rotor 28.

The bearing section 152 is open towards the rotor 28 and provided at the axial height of the sensor section 154 with the cylindrical recess 146 for direct radial mounting of the rotor shaft 144. However, here the rotor shaft 144 does not extend as far as the bottom or base of the cylindrical recess 146 in the bearing section 152, but ends beforehand at an axial spacing therefrom. For that purpose the bearing section 152 is constructed to be longer than the bearing projection 110 in the first embodiment and ends, as seen in the direction of the axis A of rotation, only shortly in front of the base section 142 of the rotor 28. A second thrust washer 158, which surrounds the rotor shaft 144 and by way of which the rotor 28 can be axially supported on the bearing section 152, is inserted between an annular end surface 156 of the bearing section 152 and the base section 142 of the rotor 28.

On the other hand, the sensor section 154 is provided with the recess 108, which is open towards the electronics chamber 46 or the electronic circuit board 92, for receiving the magnetic field sensor 36 and extends to only half the height of the cylinder section 140 of the rotor 28. As a result, also in this embodiment the magnetic field sensor 36 and the radial bearing point for the rotor shaft 144 are arranged in very compact constructional form in the rotor 28 on the side of the stator housing section 40 in one plane which extends transversely or perpendicularly to the axis A of rotation.

An electric motor driven liquid pump usable for forced lubrication of a manual transmission for motor vehicles comprises a housing, which has a liquid inlet and a liquid outlet, and an electronically commutated electric motor received therein. The latter comprises a substantially cup-shaped magnetic rotor, which is rotatable about an axis of rotation, with means for conveying liquid, an annular stator, which has a motor winding and which as seen along the axis rotation at least partly surrounds the rotor in coaxial arrangement with respect to the axis of rotation, and a magnetic field sensor for positional recognition of the rotor. The housing has in that connection a stator housing section which carries the stator, separates this from the liquid chamber in which the rotor is arranged, and as seen along the axis of rotation extends into the rotor by a housing offset which is constructed for reception of the magnetic field sensor so that the liquid pump overall has only a low constructional height.

REFERENCE NUMERAL LIST

-   10 liquid pump -   12 transmission housing -   14 flange surface external to pump -   16 housing -   18 liquid inlet -   20 liquid outlet -   22 opening -   24 transmission oil—fill level -   26 electric motor -   28 rotor -   30 blade projection -   32 motor winding -   34 stator -   36 magnetic field sensor -   38 pump housing section -   40 stator housing section -   42 liquid chamber -   44 motor housing section -   46 electronics chamber -   48 housing offset -   50 sealing element -   52 pump housing flange -   54 flange surface internal to pump -   56 pump channel -   58 funnel-shaped inlet region -   60 annular acceleration region -   62 screw-shaped conveying region -   64 tubular outlet region -   66 web -   68 bearing projection -   70 groove -   72 collar -   74 mount -   76 positioning pin -   78 shoulder -   80 fastening eye -   82 sleeve -   84 cap screw -   86 threaded bore -   88 plug collar -   90 electrical conductor -   92 electronic circuit board -   94 press-fit connection -   96 projection -   98 screw -   100 temperature sensor -   102 pole sheet -   104 ground ring -   106 annular space -   108 recess -   110 bearing projection -   112 sub-region -   114 receiving recess -   116 stator housing flange -   118 step -   120 groove -   122 first sealing section -   124 sealing lip -   126 sealing lip -   128 groove -   130 second sealing section -   132 sealing lip -   134 sealing lip -   136 shoulder -   138 opening -   140 cylinder section -   142 base section -   144 rotor shaft -   146 recess -   148 recess -   150 thrust washer -   151 base -   152 bearing section -   154 sensor section -   156 end surface -   158 thrust washer -   A axis of rotation -   R rotational direction 

1. An electric motor driven liquid pump for forced lubrication of a manual transmission for motor vehicles, comprising a housing, which has a liquid inlet and a liquid outlet, and an electronically commutated electric motor, which is received therein and which comprises a substantially cup-shaped magnetic rotor with shaped for conveying liquid upon rotation, the rotor being rotatable about an axis of rotation, an annular stator having a motor winding and at least partly enclosing the rotor in coaxial arrangement with respect to the axis of rotation as seen along the axis of rotation, and a magnetic field sensor for recognition of the position of the rotor, wherein the housing has a stator housing section which carries the stator, separates this from a liquid chamber in which the rotor is arranged, and as seen along the axis of rotation extends into the rotor by a housing offset formed to receive the magnetic field sensor.
 2. An electric motor driven liquid pump according to claim 1, wherein the housing can be flange-mounted on a liquid container by way of a flange surface external to the pump and comprises in multi-part construction in addition to the stator housing section a pump housing section, which has the liquid inlet and the liquid outlet and which together with the stator housing section bounds the liquid chamber, and a motor housing section, which together with the stator housing section bounds an electronics chamber in which at least the stator is located.
 3. An electric motor driven liquid pump according to claim 2, wherein the pump housing section and the motor housing section are constructed as plastic material parts and are welded together.
 4. An electric motor driven liquid pump according to claim 2, wherein the stator housing section has a stator housing flange which is clamped in place between the pump housing section and the motor housing section and centers the stator housing section at the motor housing section with respect to the axis of rotation.
 5. An electric motor driven liquid pump according to claim 2, wherein a sealing element is provided, which sealing element simultaneously seals the flange surface, which is external to the pump, of the housing relative to the liquid container, separates the liquid chamber from the electronics chamber and seals the electronics chamber relative to the environment.
 6. An electric motor driven liquid pump according to claim 5, wherein the flange surface, which is external to the pump, of the housing is provided with an encircling groove for reception of a first sealing section of the sealing element, which protrudes by two sealing lips beyond the flange surface external to the pump so as to seal relative to the liquid container.
 7. An electric motor driven liquid pump according to claim 5, wherein the pump housing section has a pump housing flange at which the flange surface external to the pump and a flange surface internal to the pump are formed on opposite sides, the flange surface internal to the pump being provided with an encircling groove for reception of a second sealing section of the sealing element, which protrudes by two sealing lips beyond the flange surface internal to the pump, one sealing lip co-operating with the stator housing section so as to separate the liquid chamber from the electronics chamber and the other sealing lip co-operating with the motor housing section so as to seal the electronics chamber relative to the environment.
 8. An electric motor driven liquid pump according to claim 5, wherein the sealing element consisting of an elastomeric material is attached to the pump housing section, in particular injection molded at the pump housing section to interlock therewith.
 9. An electric motor driven liquid pump according to claim 6, wherein a plurality of openings spaced apart in circumferential direction is provided between the encircling groove at the flange surface external to the pump and the encircling groove at the flange surface internal to the pump, the elastomeric material of the sealing element being injection-molded through the openings so as to interconnect the first sealing section and the second sealing section of the sealing element.
 10. An electric motor driven liquid pump according to claim 9, wherein pole sheets of the stator are embedded in the stator housing section, which is made from plastic material, by injection-molding encapsulation with plastic material.
 11. An electric motor driven liquid pump according to claim 10, wherein a temperature sensor is integrated in the housing in proximity to the liquid outlet, and received in a receiving recess in the stator housing section.
 12. An electric motor driven liquid pump according to claim 11, wherein an electronic circuit board with which the electrical parts of the liquid pump are contacted by way of press-fit connections is integrated in the housing.
 13. An electric motor driven liquid pump according to claim 12, wherein the liquid inlet of the housing is oriented transversely to the axis of rotation of the rotor.
 14. An electric motor driven liquid pump according to claim 13, wherein the rotor has a permanently magnetic outer cylinder section co-operating with the motor winding and a base section, which is constructed as an impeller on the side remote from the housing offset of the stator housing section and is injection-molded from a magnetic material, which is incorporated in plastic material, directly on a rotor shaft rotatably mounted in the housing.
 15. An electric motor driven liquid pump according to claim 14, wherein the rotor shaft is mounted on both sides of the base section at least radially directly in the housing, namely, in the housing offset of the stator housing section and in a bearing projection of the pump housing section.
 16. An electric motor driven liquid pump according to claim 1, wherein pole sheets of the stator are embedded in the stator housing section, which is made from plastic material, by injection-molding encapsulation with plastic material.
 17. An electric motor driven liquid pump according to claim 1, wherein a temperature sensor is integrated in the housing in proximity to the liquid outlet and received in a receiving recess in the stator housing section.
 18. An electric motor driven liquid pump according to claim 1, wherein an electronic circuit board with which the electrical parts of the liquid pump are contacted by way of press-fit connections is integrated in the housing.
 19. An electric motor driven liquid pump according to claim 1, wherein the liquid inlet of the housing is oriented transversely to the axis of rotation of the rotor.
 20. An electric motor driven liquid pump according to claim 1, wherein the rotor has a permanently magnetic outer cylinder section co-operating with the motor winding and a base section, which is constructed as an impeller on the side remote from the housing offset of the stator housing section and is injection-molded from a magnetic material, which is incorporated in plastic material, directly on a rotor shaft rotatably mounted in the housing. 